超临界流体触媒作用下石墨金刚石转变

CONVERSION OF GRAPHITE-TO-DIAMOND ASSISTED BY A FLUID CATALYST UNDER HIGH PRESSURE AND HIGH TEMPERATURE

研究了超临界流体CO2 在石墨 金刚石转变中的触媒作用。实验中 ,采用Ag2 O作为流体触媒的先驱材料 ,在 7.7GPa压力下 ,Ag2 O在 1 2 0 0℃分解成Ag和O2 ,O2 与石墨套管在高温高压下反应形成CO2 超临界流体。研究结果表明 ,在 7.7GPa和 1 5 0 0℃以上温度条件下 ,石墨在CO2 流体触媒的作用下可转变为金刚石晶体 ,在 1 5 0 0～ 1 70 0℃温度范围内合成出的金刚石具有完好的八面体形貌 ,与天然金刚石的生长特征非常相似。

The catalyst role of supercritical fluid CO 2 in the conversion of graphite-to-diamond at high pressure and high temperature has been confirmed experimentally.The complete transformation from graphite to diamond is achieved at 1800～2000℃ within 2～0.5h under the pressure of 7.7GPa.The change in temperature leads to morphology modification of the diamonds formed in the experiments:Diamonds with an irregular shape crystallize at 1800～2000℃ and the octahedral morphology crystallize at 1500～1700℃.